Catalytic fast pyrolysis of sugarcane bagasse pith with HZSM-5 catalyst using tandem micro-reactor-GC-MS

Fast pyrolysis of biomass is praised as an efficient and feasible process to selectively convert lignocellulosic biomass into bio-fuels and bio-chemicals. Pith of sugarcane bagasse could be an attractive lignocellulosic waste from depithing process from pulp and paper mill, which can utilize for production of biofuel and added value products. In this study, we employed a tandem micro-reactor coupled with gas chromatography-mass spectroscopy to investigate the products distribution from pith of sugarcane bagasse via catalytic fast pyrolysis. In the operating conditions, pyrolysis temperature and HZSM-5 catalyst had significant effect on products and distributions. An increase in the pyrolysis temperature from 400°C to 550°C led to an increase in the yield of phenolic compounds (6.3%, w/w%), followed decrease at higher temperature. The maximum carboxylic acids (10.6%) and furfural (3.5%) were obtained at lower temperature. At presence of HZSM-5 catalyst, the selectivity of aromatics such as benzene, toluene, indene, and naphthalene were improved.     

Comprehensive research of in situ upgrading of sawdust fast pyrolysis vapors over HZSM-5 catalyst for producing renewable light aromatics

Catalytic fast pyrolysis of sawdust was investigated over HZSM-5 zeolites (SiO₂/Al₂O₃ = 25, 50 and 80) in a drop tube quartz reactor for production of green aromatics and olefins. The effects of temperature, weight hourly space velocity (WHSV), SiO₂/Al₂O₃ ratio and atmosphere on yield and selectivity of aromatics were investigated. The results show that almost all small organic oxygen species in initial volatiles were converted into gaseous hydrocarbons and aromatics after in situ catalysis of HZSM-5. HZSM-5 whose SiO₂/Al₂O₃ is 25 exhibited the best performance with the aromatics yield of 21.8% on carbon basis at 500 °C. However, HZSM-5 can act as cracking and aromatization catalyst, but not as an agent to promote hydrogenation. The ESI-MS revealed the most abundant macromolecular compounds in initial volatiles were O₁O₂₇ species with 0–20 double bond equivalent (DBE) values and 5–40 carbon numbers, while the macromolecules were O₁O₉ species with 2–12 DBE and 10–25 carbon numbers after upgrading. Furthermore, the formation of coke on catalysts was influenced by the properties of HZSM-5 and experimental conditions.     

Fast and catalytic pyrolysis of xylan: Effects of temperature and M/HZSM-5 (M= Fe,Zn) catalysts on pyrolytic products

Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was employed to achieve fast pyrolysis of xylan and on-line analysis of pyrolysis vapors. Tests were conducted to investigate the effects of temperature on pyrolytic products, and to reveal the effect of HZSM-5 and M/HZSM-5 (M= Fe, Zn) zeolites on pyrolysis vapors. The results showed that the total yield of pyrolytic products first increased and then decreased with the increase of temperature from 350°C to 900°C. The pyrolytic products were complex, and the most abundant products included hydroxyacetaldehyde, acetic acid, 1-hydroxy-2-propanone, 1-hydroxy-2-butanone and furfural. Catalytic cracking of pyrolysis vapors with HZSM-5 and M/HZSM-5 (M= Fe, Zn) catalysts significantly altered the product distribution. Oxygen-containing compounds were reduced considerably, and meanwhile, a lot of hydrocarbons, mainly toluene and xylenes, were formed. M/HZSM-5 catalysts were more effective than HZSM-5 in reducing the oxygen-containing compounds, and therefore, they helped to produce higher contents of hydrocarbons than HZSM-5.     

Catalytic conversion of fast pyrolysis oil to hydrocarbon fuels over HZSM-5 in a dual reactor system

The catalytic conversion of fast pyrolysis bio-oil to hydrocarbon fuels was studied over HZSM-5 at atmospheric pressure. Experiments were conducted in a dual reactor system having two reactors in series. The temperatures in these reactors were in the range 340–400°C (first reactor) and 350–450°C (second reactor). The bio-oil was co-processed with tetralin in all the runs. The objective was to maximize the organic distillate product with a high concentration of aromatic hydrocarbons. The maximum amount of organic distillate in the effluent from the second reactor was 21 wt% of the bio-oil feed and the highest concentration of aromatic hydrocarbons was 76 wt% of the distillate. The dual reactor system was particularly beneficial when the temperature in the first reactor was low. Thus, with the first reactor at 340°C, the yields of organic distillate and aromatic hydrocarbons were 15–16 wt% and 8–11 wt% of wood, respectively, which are nearly two-fold compared to those from a single reactor system operated at 340°C (7.8 wt% and 4.8 wt%). Under the above conditions, the coke plus char yields were 25–26 wt% of wood which are up to 10 wt% lower than from the single reactor system at 340°C (29 wt%).     

In situ hydrodeoxygenation upgrading of pine sawdust bio-oil to hydrocarbon biofuel using Pd/C catalyst

Hydrodeoxygenation (HDO) is effective for upgrading bio-oil to biofuel. However, the upgrading cost increased due to the high consumption of external hydrogen. In this paper, the hydrogen generated from cheap water using zinc hydrolysis for in situ bio-oil HDO was reported. The effect of different temperatures (200 °C, 250 °C and 300 °C) on bio-oil HDO over Pd/C catalyst was investigated in a batch reactor. The results show that 250 °C yielded biofuel with the highest heating value at 30.17 MJ/kg and the highest hydrocarbons content at 24.09%. Physicochemical properties including heating value, total acid number and chemical compositions of the produced biofuels improved significantly in comparison with that of the original bio-oil.     

Effect of agglomerated NiMo HZSM-5 catalyst for the hydrocracking reaction of Jatropha curcas oil

Catalytic hydrocracking of Jatropha curcas oil over ZSM-5-supported catalyst was carried out to produce biofuels. The agglomerated catalyst was successfully prepared by a simple technique and characterized using several techniques. The hydrocracking reactions were studied in a batch reactor at 400°C under initial H₂ atmosphere for 2 h reaction using 1 wt% catalyst loading. The effect of agglomerated catalysts on the yield of liquid fuels and hydrocarbon number distribution was discussed. The results showed that the hydrocarbon distribution largely changed depending on the type of catalyst. The powder catalysts seem selectively to produce hydrocarbon in the diesel range (C₁₂–C₂₂), whereas gasoline (C₅–C₁₂) and kerosene (C₈–C₁₆) had high formation after agglomerated catalyst was used. For agglomerated NiMo ZSM-5 catalyst, hydrocracking of Jatropha curcas oil produced more hydrocarbons in the gasoline range (about 43.23% in liquid fuels).     

In-situ catalytic upgrading of biomass-derived vapors using HZSM-5 and MCM-41: Effects of mixing ratios on bio-oil preparation

In this paper, two molecular sieves with different pore sizes, namely HZSM-5 and MCM-41, were mixed using different ratios and used in the in-situ catalytic pyrolysis of rape straw. The effects of different HZSM -5 and MCM -41 mixing ratios on the quality of the bio-oil were studied by physicochemical properties, product yields and compositions. Moreover, Brunauer-Emmett-Teller (BET) catalyst analysis was performed. The results showed that the liquid yield and organic phase decreased first and then increased, whereas the gas yield showed an opposite trend. The density, O/C and kinematic viscosity of the bio-oil organic phase decreased first then increased, whereas the H/C, pH values and higher heating values initially increased, then declined. The oxygen content, H/C, O/C, kinematic viscosity, density, higher heating value and pH value of the bio-oil organic phase obtained at 1:1 mixed ratio were 12.81%, 1.701, 0.126, 5.06 mm²/s, 0.94 g/cm³, 34.31 MJ/kg and 5.41, respectively. The organic phase included numerous organic compounds, such as carboxylic acids, aldehydes, ketones, hydrocarbons, alcohols, ethers and esters. The hydrocarbon content in the bio-oil organic phase gradually increased and the carbonyl groups content gradually decreased as the MCM-41 content increased from 0 to 50%. In contrast, the hydrocarbon content gradually decreased and the carbonyl groups content gradually increased as the MCM-41 content increased from 50% to 100%. The hydrocarbon and carbonyl groups contents were 53.83% and 6.35%, respectively, at the MCM-41 content of 50%. The mixed catalyst activity increased with the increase in MCM-41 content (up to 50%), and tended to be stable once the MCM-41 contents surpassed 50%.     

Highly selective hierarchical ZSM-5 from kaolin for catalytic cracking of Calophyllum inophyllum oil to biofuel

Upgrading the inferior properties of Calophyllum inophyllum oil via catalytic cracking into biofuel required a porous heterogeneous acid catalysts. Hierarchical ZSM-5 (Hi-ZSM-5(K)) produced from desilication of kaolin-derived ZSM-5 was employed as catalyst and the activity was compared with hierarchical ZSM-5 obtained from templating method (Hi-ZSM-5(T)). Catalytic cracking of Calophyllum inophyllum oil was carried out in one-pot reaction at 475 °C for 120 min under the flow of H₂ and the products analysed using GC-MS were consisted of the mixtures of alkane, alkene, oxygenated carbon and aromatics compound. The advantages of desilication method for the formation of highly selective hierarchical ZSM-5 was observed when the catalyst exhibited enhanced acidity with mesopores diameter of 2–5 nm to give 93% conversion and high selectivity towards light C7–C9 hydrocarbons. However, Hi-ZSM-5(T) showed low acidity to give only 43% conversion, and selectivity towards C11–C12 hydrocarbons due to the mesopores diameter of 3–12 nm. The activity of hierarchical ZSM-5 was also compared with microporous ZSM-5 that produced biofuel with approximately equal distribution of C5–C18 hydrocarbons. The role of hierarchical structures was further discussed on the composition of aromatics compound, oxygenates content and alkene/alkane ratios of the biofuel.     

Enhanced liquid biofuel production from crude palm oil over synthesized NiMoW-ZSM-5/MCM-41 catalyst

Micro-mesoporous ZSM-5/MCM-41 composites were prepared and then loaded with varied contents of NiMoW by the wet impregnation method. The hydrocracking conversion of crude palm oil to liquid biofuels with the prepared catalysts was carried out in a batch reactor at 400°C for 2 h. ZSM-5/MCM-41 composite exhibited 51.00% conversion with a yield of 9.23% gasoline, 20.60% kerosene, and 21.17% diesel. Upon loading of NiMoW, the catalysts exhibited an improved conversion (≥ 62.60%) and a reduced formation of coke, which resulted from combined properties of ZSM-5 with MCM-41 and the presence of dispersed NiMoW. The contents of impregnated metals also affected the performance of catalysts. Using ANOVA analysis (p < 0.05), we found that 8:8:8 wt.% NiMoW-ZSM-5/MCM-41 catalyst was suitable for the production of biofuels, when considering the efficiency and cost-effectiveness.     

Ga/ZSM-5催化酚醛树脂热解选择性制备单环芳烃的研究

开发一系列用于酚醛树脂快速热解的Ga改性ZSM-5催化剂,并进行全面的催化剂表征,包括X射线衍射(XRD)、氮气吸附脱附、氨气程序升温吸附(NH₃-TPD)和透射电子显微镜(TEM)等,以阐明催化剂的结构特性。Ga物种显著调节了ZSM-5分子筛酸性位点的分布和孔结构,有利于高温下促进热解脱氧反应的进行,同时优化了择形催化性能。重点讨论了Ga负载量、热解温度、催化剂与酚醛树脂质量比和升温速率等参数对热解油组成分布的影响规律。与母体H-ZSM-5催化剂相比,0.5Ga/ZSM-5在酚醛树脂快速热解中催化生产单环芳烃的效率更高,且更能有效抑制酚类化合物的生成。当热解温度为800℃、升温速率为10℃/ms时,单环芳烃的相对含量达到64.1%。     

Integrated production of aromatic amines,aromatic hydrocarbon and N-heterocyclic bio-char from catalytic pyrolysis of biomass impregnated with ammonia sources over Zn/HZSM-5 catalyst

By introducing exogenous nitrogen during biomass pyrolysis under nitrogen-rich conditions, high-value nitrogen-containing products, i.e., nitrogen-rich char and oil may be produced. Based on the cogeneration of high-value nitrogen products from biomass, biomass nitrogen-enriched pyrolysis was performed in a fixed bed with different sources and contents of ammonia. The yields, composition and characteristics of the products were investigated. Moreover, the formation mechanism of N-containing species was explored in depth for the pyrolysis and catalytic pyrolysis with HZSM-5 and Zn/HZSM-5 catalysts via elemental analysis, XPS, FTIR and BET. The results showed that ammonia impregnation could promote a Maillard reaction, reduce the content of small aldehydes and ketones, and produce a nitrogen-enriched bio-oil. The contents of N-containing species and phenolic substances in the pyrolysis oil of biomass impregnated with 10% urea reached 15.66% and 56.69%, respectively. Moreover, the nitrogen on the coke surface after pretreatment was mainly composed of CN, CN and NCOO functional groups. The bio-char generated abundant pyridinic-N, pyrrolic-N, quaternary-N, and pyridone-N oxides. The presence of urea introduced many alkaline N-containing functional groups on the surface of the bio-char and promoted the transformation of nitrogen from amides and imides to heterocyclic nitrogen with higher thermal stability. Furthermore, Zn was an excellent catalyst for the Maillard reaction, and the Zn/HZSM-5 catalyst had a higher selectivity for aromatic hydrocarbons (96.98% for biomass and 86.48% for urea/biomass) and N-containing heterocyclic compounds, such as indoles (6.16% for biomass and 13.51% for urea/biomass). Additionally, the coke content decreased, and the catalyst deactivation decreased.     

Hydrogen production by aqueous phase reforming of phenol over Ni/ZSM-5 catalysts

Hydrogen production from biomass in particular bio-oils appears interesting as bio-oils is easy to transport and storage with high conversion towards hydrogen. Phenol as presentation of lignin-derived bio-oils was chosen in this paper and was studied under aqueous phase reforming (APR) reaction using Nickel-based catalysts with ZSM-5 as support. The catalysts were synthesized by incipient wetness impregnation, and their physical and chemical properties were characterized by XRD, NH₃-TPD, H₂-TPR, SEM, TEM and N₂ adsorption–desorption. Ni/ZSM-5 was studied with different Si/Al molar ratio and different Ni content on APR of phenol. The reactant concentration, reaction pressure and temperature were also evaluated. Ni/ZSM-5 with Si/Al molar ratio of 25 and nickel content of 16% exhibited the highest catalytic activity. Hydrogen production were maximized over the temperature of 240 °C, reaction pressure of 4 MPa and the phenol concentration of 0.2 mol/L.     

Preparation and characterization of a bioanode (GC/MnO2/PSS/Gph/Frt/GOx) for biofuel cell application

In this study, a bioanode (GC/MnO₂-PSS-Gph/Frt/GOx) was developed by depositing a manganese dioxide-polystyrene sulfonate-graphene (MnO₂-PSS-Gph) composite containing ferritin (Frt) as mediator and glucose oxidase (GOx) as a catalytic enzyme on a glassy carbon (GC) electrode. The GOx oxidize the glucose to gluconolactone with the release of electrons. The composite was prepared by extending the Hummers method and characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and Fourier transform infrared (FTIR) spectroscopy. The electrochemical functioning of the fabricated bioanode was investigated by cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge techniques. A maximum current density of 2.7 ± 0.2 mAcm⁻² associated with the bioanode was observed at the scan rate of 100 mVs⁻¹ in a potential range from −0.2 to 0.8 V having a glucose concentration of 40 mM. The surface concentration of GOx on the prepared bioelectrode was found to be 2.3 × 10⁻¹⁰ mol cm⁻² and rate constant for the electron transfer was calculated to be 3.89 s⁻¹.     

Bi-reforming of methane on Ni/SBA-15 catalyst for syngas production: Influence of feed composition

Bi-reforming of methane (BRM) was evaluated for Ni catalyst dispersed on SBA-15 support prepared by hydrothermal technique. BRM reactions were conducted under atmospheric condition with varying reactant partial pressure in the range of 10–45 kPa and 1073 K in fixed-bed reactor. The ordered hexagonal mesoporous SBA-15 support possessing large specific surface area of 669.5 m² g^?1 was well preserved with NiO addition during incipient wetness impregnation. Additionally, NiO species with mean crystallite dimension of 14.5 nm were randomly distributed over SBA-15 support surface and inside its mesoporous channels. Thus, these particles were reduced at various temperatures depending on different degrees of metal-support interaction. At stoichiometric condition and 1073 K, CH₄ and CO₂ conversions were about 61.6% and 58.9%, respectively whilst H₂/CO ratio of 2.14 slightly superior to theoretical value for BRM would suggest the predominance of methane steam reforming. H₂ and CO yields were significantly enhanced with increasing CO₂/(CH₄ + H₂O) ratio due to growing CO₂ gasification rate of partially dehydrogenated species from CH₄ decomposition. Additionally, a considerable decline of H₂ to CO ratio from 2.14 to 1.83 was detected with reducing H₂O/(CH₄ + CO₂) ratio due to dominant reverse water-gas shift side reaction at H₂O-deficient feedstock. Interestingly, 10%Ni/SBA-15 catalyst was resistant to graphitic carbon formation in the co-occurrence of H₂O and CO₂ oxidizing agents and the mesoporous catalyst structure was still maintained after BRM. A strong correlation between formation of carbonaceous species and catalytic activity was observed.     

Py-GC/MS技术用于Chaetoceros sp. 硅藻的催化热解研究

采用热裂解−气质联用（Py-GC/MS）技术研究Chaetoceros sp. 硅藻粉末的催化热解特性。以HZSM-5为催化剂,考察了不同Si/Al比的HZSM-5催化剂对硅藻热解产物的影响,并考察了催化剂的使用量、热解升温速率、热解反应时间对产物的影响。结果表明：未加催化剂时,硅藻热解产物以脂肪酸为主,含量为50.05%,苯系物含量仅为0.87%;加入HZSM-5催化剂后,硅藻热解产物中脂肪酸含量减少,芳香类化合物显著增加。热解实验结果发现,Si/Al比为38、硅藻和HZSM-5比例为1∶9、热解速率10 000℃/s、热解时间为10 s时,能得到较理想的热解产品,其中苯系物产率可达57.76%,脂肪酸含量为2.63%。这说明HZSM-5（38）具有较好的脱氧和芳构化功能,有利于硅藻催化热解生成高品质的生物油产品。     

Structure and catalytic properties of Ni/MWCNTs and Ni/AC catalysts for hydrogen production via ammonia decomposition

The structure and catalytic properties of nickel catalysts supported on multi-wall carbon nanotubes (MWCNTs) and on three different types of activated carbon (AC) were studied. The surface areas of AC carriers were defining the size of supported nickel particles. Large surface area of AC led to small Ni nanoparticles and high Ni dispersion. Turnover frequency (TOF_NH3) of ammonia decomposition decreased with decreasing of Ni particle size. The highest degree of ammonia conversion was observed on Ni/AC prepared by using of AC support with largest surface area. The catalytic activity of Ni/MWCNTs was much higher than catalytic activity of the studied Ni/AC catalysts. The synergic nickel-support interaction and special electronic conductivity properties of MWCNTs were responsible for high catalytic activity of Ni/MWCNTs catalyst.     

Hydrogen promotion by Co/SiO2@HZSM-5 core-shell catalyst for syngas from plastic waste gasification: The combination of functional materials

In the present work, a core-shell structured Co/SiO₂@HZSM-5 catalyst was prepared for hydrogen production from syngas of plastic waste gasification. The cobalt catalyst was coated with HZSM-5 shell through a hydrothermal process, and the Co/SiO₂@HZSM-5, with different loadings of HZSM-5 (e.g., 10–30 wt %) exhibited excellent activity and durability for dehydrogenation reactions. The amount of HZSM-5 was found to be an important factor for hydrogen production. Temperature-programmed reduction with H₂ and temperature-programmed desorption of ammonia was applied to determine the active site and the acidity of prepared catalyst, respectively. The prepared Co/SiO₂@HZSM-5 was tested through reforming of plastic gasification syngas and shown superior hydrogen production ability (∼90%) and stability (over 15 h). The effects of reduction-oxidation behavior on the catalytic performance were also discussed.     

Highly efficient catalytic pyrolysis of biomass vapors upgraded into jet fuel range hydrocarbon-rich bio-oil over a bimetallic Pt–Ni/γ-Al2O3 catalyst

Catalytic pyrolysis is an effective method for converting biomass to value-added chemicals. However, the development of cost-effective catalysts remains a major challenge. In this study, a highly efficient bimetallic Pt–Ni catalyst (Pt to Ni ratio = 0:1, 2:1, 1:1, 1:2, 1:0) was fabricated and used for catalytic biomass pyrolysis upgrading into hydrocarbon-rich bio-oil with pyrolysis-gaschromatography × gaschromatography/mass spectrometry (Py-GC1 GC/MS). The product yield and selectivity of upgraded bio-oil, thermal properties, kinetic and deactivation mechanisms were also determined to investigate the reaction mechanism. It was determined that Pt addition strengthened the NiO and alumina interaction and improved nickel dispersion, promoting CO hydrogenation. Bimetallic catalysts had a higher stability and activity owing to synergistic action of platinum and nickel on γ-Al₂O₃, and the surface oxygen vacancies were derived from the electron transfer of Pt to Ni and the higher number of super acid-base sites, which inhibited coke deposition. In addition, the higher valence Pt (Pt²⁺) in the catalyst was favorable for decarboxylation and hydrodecarbonylation reactions. Various metal ratios were employed, and the Pt–Ni/Al = 1:2 catalyst exhibited an excellent catalytic performance, achieving highest peak areas of desired hydrocarbons and aromatic hydrocarbons at 52.67% and 40.25%, respectively, and the lowest peak area of deposited coke at 7.26%, along with a 13.98% weightloss rate.     

Photo-assisted electrolysis of urea using Ni-modified WO3/g-C3N4 as a bifunctional catalyst

Urea splitting to produce H₂ is as an energy-saving alternative to water electrolysis. However, efficient catalysts are required for the practical implementation of urea splitting because of the high overpotentials of the urea oxidation reaction and the hydrogen evolution reaction. Herein, a Ni-modified direct Z-scheme photocatalyst for the urea oxidation and hydrogen evolution reactions was synthesized by electroplating a WO₃/g-C₃N₄ nanocomposite on Ni-decorated carbon felt (WO/CN–Ni@CF). The 2D/2D nanostructure of the as-synthesized WO₃/g-C₃N₄ composite was confirmed by SEM and TEM. The WO/CN–Ni@CF catalyst electrode exhibited excellent bifunctional photocatalytic activity for the urea oxidation and hydrogen evolution reactions. Consequently, the potential required to generate 100 mA cm^?2 in an illuminated photoelectrochemical cell using WO/CN–Ni@CF as the anode and the cathode was reduced from 1.80 to 1.50 V. The photoelectrochemical cell exhibited good stability for 18 h with stable H₂ generation.